The present invention relates generally to end-of-movement damping for doors of motor vehicles, and more specifically to a return device for assisting in the re-closing of a vehicle door after the opening motion has been damped.
Wide opening doors for motor vehicles (i.e., a door with a large range of movement to clear the door opening) have several advantages. From a consumer standpoint, a wider opening is beneficial when needing to load large items into the vehicle. From a manufacturer standpoint, since many assembly operations are performed after a door has been installed but with the door swung open to its maximum extent (e.g., connecting wiring or other components in the hinge area between the forward edge of the door and the door frame), these assembly operations become easier the greater the opening range of the door.
A disadvantage of a wide opening door becomes evident when a vehicle occupant attempts to close the door. After being seated inside the vehicle, the occupant may be at too great a distance from the door pull handle to be able to conveniently reach it. In addition, the door must initially be pulled in the radial direction (i.e., toward the back of the vehicle instead of toward the occupant). This results in a non-ergonomic motion being required of the seated occupant since the initial sideways movement has to be generated with the arm outstretched.
So that the manufacturing advantage of a wide opening door can be realized without creating customer inconvenience when closing the door, it is known to install door hinges with a wide range of motion to facilitate the necessary assembly operations. Once those operations are completed at the assembly plant, a door check link is connected between the door and door frame that thereafter restricts the range of door motion so that the vehicle occupant is better able to reach it for closing. However, it becomes more difficult to load large items through the door opening because of interference from the door.
Door check links have traditionally provided detents to preferentially hold an open door in various predetermined positions, including at the fully open position. More recently, door holding units have been introduced using hydraulic cylinders to provide positive retention of a manually positioned door at infinitely many positions across the full range of door motion. One example of such a door holding unit is the DORSTOP® device from Stabilus GmbH of Koblenz, Germany. As shown in U.S. Pat. No. 7,066,310, it is also known to provide damping (i.e., energy absorption) at the fully open end of the door travel using a separate end-damping piston that is acted upon by a main holding piston. In the prior art, even though a reset spring may be provided to reset the end-damping piston to its original position after being released by the holding piston, the door has been kept in its fully open position by the holding piston until the door is manually moved out of the open position by the user. In fact, the reset spring was intentionally designed not to induce any door motion since the device was meant to hold the door in any position in which is was placed by the user.